Self-adjustable backrest device

ABSTRACT

The self-adjustable backrest device supplements a seat surface such that said seat surface is a previously existing one and what is covered by the object of this invention adds a backrest or improves the existing one, for which purpose it comprises a mobile plate on which the user rests, wherein said plate swivels on a horizontal shaft that passes through a first set of hubs connected to the plate, that shaft being associated with a second set of hubs connected to a support that may be the backrest itself of the chair or easy chair on which the self-adjustable backrest is going to be used, in which case it will be referred to as pre-existing backrest, or it may be a fixed backrest which forms part of the device, in which case it will be referred to as backrest of the device. The device may include fixing elements to prevent its movement, such as legs, pegs, or a flap.

TECHNICAL FIELD

The present invention relates to a self-adjustable backrest device, which has an automatic means of position adaptation for the user's comfort. It is applicable to all types of seats: chairs, sofas, easy chairs, wheel chairs, automotive seats, etc, and even as an independent element to be placed on the floor.

STATE OF THE ART

For the manufacture of vehicle, office or of any other type of seats, more or less complex systems are applied so the backrest adapts to the user's position.

Thus, for example, patent ES2118081T3 refers to a chair comprising a seat and backrest connected to each other, characterised in that the backrest presents certain movement in being associated with two horizontal shafts, one on which it swivels, and another that limits its movement.

Patent US2005035636A1 discloses a chair of the type comprising a seat and backrest connected to each other, being self-adjustable, characterised by comprising a backrest formed by back-support plate, supported by a horizontal shaft joint provided on a support, such joint being at a certain distance from the base of the backrest, preferably in an area at an average height of the backrest, and has a rotation spring cushioned and limited by a rotation limit system, and when the plate is in resting position, it is in an approximately vertical position. The plate, the support and the joint are included in a semi-rigid casing.

None of the cited patents provides lumbar support.

Patent WO9427472A1 describes a chair comprising a seat and backrest connected to each other characterised by comprising a backrest/back support plate, supported by a horizontal shaft joint.

Patent ES2255466A1 refers to a self-adjustable chair characterised in that it comprises a continuous single piece that serves as backrest and seat and is supported by a joint.

Patent U.S. Pat. No. 6,435,615B1 discloses a chair comprising a seat and backrest connected to each other, characterised in that the backrest is supported by a horizontal shaft joint.

Patent DE20113075U1 refers to a chair, which comprises seat and backrest, characterised in that the backrest comprises an arm with two shafts, a lower one that associates it with the seat and another upper one that regulates the position of the plate on which the user rests.

None of these patents refer to an independent backrest that can be coupled to different chairs, easy chairs or any other type of seat.

Patent US2005168044A1 describes a seat backrest that has a lower extensions suitable to be pushed into the ground, such as at the beach, and serves as backrest for users sitting on the ground.

Patent WO0117398A1 discloses a self-adjustable seat that is supported on the ground with an adaptation system not comprising a horizontal shaft.

None of the patents cited refer to an independent backrest, suitable to be installed in any type of chair, easy chair, armchair, or even on the floor itself that protects the lumbar area regardless of the posture adopted by the user and which lifts the buttocks relaxing the pressure thereon.

BRIEF EXPLANATION OF THE INVENTION

The invention relates to a self-adjustable backrest device, which protects the lumbar area and relaxes the pressure on the buttocks.

The backrest is self-adjustable, which means that it needs no control or command.

The device referred to supplements a seat surface such that the seat surface exists previously and what is covered by the object of this invention is that it adds a backrest or improves the already existing one.

The self-adjustable backrest assembly comprises a mobile plate on which the user rests, wherein said plate swivels on a horizontal shaft that passes through a first set of hubs connected to the plate, that shaft being associated with a second set of hubs connected to a support that may be the backrest itself of the chair or easy chair on which the self-adjustable backrest is going to be used, in which case it will be referred to as pre-existing backrest, or it may be a fixed backrest which forms part of the device, in which case it will be referred to as backrest of the device.

At least one of the sets of hubs is adjustable in height and thus, height variation of the first set of hubs will vary the relative point on which the plate swivels altering the lever while height variation of the second set of hubs will alter the height at which the plate is located.

Hub refers herein to any element that serves as support to the shaft allowing its rotation.

The backrest of the device may have different dimensions based on, among other things, the surface on which it should be supported.

The plate has an initial position, in the absence of forces applied by the user or at his or her will, and a balancing run that can be limited by a maximum position and a minimum position.

The ideal initial or resting position is preferably close to the vertical line although that can vary depending on the angle of the pre-existing backrest or support on which the backrest of the device rests.

This resting position is obtained thanks to the action of a rotation spring in the resting position of which the plate is in an approximately vertical position where said rotation spring can be cushioned for user comfort.

While not being used, the plate is forced into the resting position by the rotation spring, which is capable of overcoming the weight of the plate and bringing it to the initial position and holding it in that position, but allowing it to yield under the pressure exerted by the user when sitting down without the user perceiving an ejection force.

Optionally, the run of the plate can have a limit.

Preferably, the assembly of mobile plate, first and second set of hubs, shaft and the support will be included in a is semi-rigid casing so that the user will not see these mechanical elements and the risk of getting pinched is reduced.

In line with the above, the lower part of the plate may incorporate an elastic element which closes the space between the plate and the seat surface, reducing the risk of pinching an object or user body part which may be inserted therein. This elastic element will usually connect the seat surface to the plate, and may be made of a rubber fabric which, in addition, can help the plate to return to the vertical position, whereby two benefits are achieved with a single element.

The assembly comprising the plate, the first and second set of hubs, the shaft and the support is suitable to be associated with a chair, easy chair or sofa, among others, which can include car seats, which are more complex.

Once the self-adjustable backrest device has been installed, the user will sit on a seat surface, that is approximately horizontal and pre-existing, and will support the back on the self-adjustable backrest device.

Preferably, the height of the shaft will be adjustable and will be arranged at between 12 and 33 cm above the user's seat surface, and preferably between 18 and 27 cm.

For the case in which the self-adjustable backrest is not supported on a pre-existing backrest on the chair or easy chair for its location, the self-adjustable backrest may incorporate various accessory elements to stay affixed and prevent it from moving under the user's weight.

Thus, for example, in a possible embodiment, the device can incorporate suitable pegs to dig into soft ground such as earth or sand.

Another possible embodiment can incorporate non-skid legs to affix it to smooth surfaces.

In a third embodiment, the device can incorporate a flap with which the user affixes the support with his or her own weight, which will be useful when, for example, the user wants to read in bed and lean on the device.

The seat device may have armrests or any other element without altering the nature of the invention. Also, the plate may have a curvature, cushioning, flexibility, rigidity, or any other measure to increase user comfort.

Lastly, the material will be wood, plywood, plastic, metal, fabric, wicker, or any other,

The plate may be separated from the shaft to facilitate the tasks of cleaning, repair, or adjustment, among others.

DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, the following figures are included.

FIG. 1 shows the invention in an embodiment which uses the backrest itself of the chair where the device is used as a fixed backrest and thus we find the mobile plate (1), the first set of hubs (2) connected to the mobile plate, the shaft (3) and the second set of hubs (4) connected to the support, in this case a pre-existing backrest (5). The seat surface (10), in this case a chair, is also shown.

FIG. 2 graphically shows an adjustable backrest device that does incorporate a fixed backrest in this case prepared to lean on the backrest of an armchair, with the mobile plate (1), the first set of hubs (2), the shaft (3), the second set of hubs (4) and the backrest of the device (6).

FIG. 3 shows an embodiment wherein the backrest of the device (6) that presents a triangular cross-section, incorporates pegs (7) for anchoring the backrest to a soft and penetrable ground, such as earth or sand.

FIG. 4 shows an embodiment wherein the backrest of the device (6) incorporates bases (8) suitable for affixing the device onto smooth ground.

FIG. 5 shows an embodiment wherein the backrest of the device incorporates a flap (9) between the seat surface (10), in this case the floor, and the user such that, in this way, the user, prevents the movement of the device with his or her own weight.

EMBODIMENTS OF THE INVENTION

Briefly described hereunder is an embodiment of the invention, by way of example and without limiting the scope thereof.

The self-adjustable backrest that is supplemented with a seat surface comprising:

A mobile plate (1) having a sufficient size to cover the user's back from the coccyx to the area of the shoulder blades.

A horizontal shaft (3) on which the aforementioned mobile plate swivels, the said shaft being supported by a first set of hubs (2) connected to the mobile plate and a second set of hubs (4) connected to the backrest of the device (6).

A rotation spring that keeps the plate in an approximately vertical position when it is in resting position, i.e., when there is no external force acting thereupon.

The device is resting on a seat surface (10), such as a bed or the floor.

The first set of hubs (2) that is adjustable in height is connected to the mobile plate. When varying the relative height of the first set of hubs, and therefore the shaft, in relation to the plate, the point on which the plate swivels is altered modifying the torque exerted by the plate.

The shaft (3) is also associated with the second set of hubs (4) that are connected to the backrest of the device (6).

In this embodiment the second set of hubs is further height-adjustable, and, by varying its height, the height of the plate and the shaft are modified in relation to the seat surface.

The shaft on which the plate swivels is located at a height of 23 cm, the normal height being between 12 and 33 cm from the seat surface and, preferably between 18 and 27 cm

The action of the first and second set of hubs, and the horizontal shaft associating them, allows the mobile plate to swivel on the backrest of the device such that the greater the force exerted by the user on the upper part of the mobile plate, the greater the action on the lumbar area ,reducing the pressure on the buttocks being lifted.

In this embodiment being explained, to prevent the movement of the self-adjustable backrest device due to the horizontal force exerted by the user when leaning thereon, it comprises a flap by way of brace on which the user sits which, with his or her weight, prevents the assembly from moving. 

1. *Self-adjustable backrest device of the type which supplement a seat surface characterized in that it comprises a mobile plate (1), a first set of hubs (2) connected to the mobile plate, a horizontal shaft (3) on which the plate swivels and a second set of hubs (4) associated on the one hand with the horizontal shaft and on the other hand connected to a support on which the self-adjustable backrest is disposed and configured as a pre-existing backrest or a fixed backrest which is a part of the device, wherein the shaft is disposed at a distance from the seat surface (10) of between 12 and 33 cm.
 2. *Self-adjustable backrest device of claim 1 wherein it further comprises a rotation spring that associates the plate and the horizontal shaft forcing their relative position, preferably cushioned, in the resting position of which the plate is in an approximately vertical position.


3. *Self-adjustable backrest device of claim 1 wherein the shaft run is limited by a stop.
 4. Self-adjustable backrest device of claim 1 wherein the assembly consisting of the mobile plate, first and second set of hubs and the support is included in a semi-rigid casing.
 5. Self-adjustable backrest device of claim 1 wherein the lower part of the plate has an elastic element that closes the space between the plate and the seat surface.
 6. Self-adjustable backrest device of claim 1 wherein the support is a backrest of the device (6) and is fixed.
 7. Self-adjustable backrest device of claim 1 wherein the backrest of the device (6) has pegs (7).
 8. Self-adjustable backrest device of claim 1 wherein the backrest of the device (6) has a flap (9).


9. *Self-adjustable backrest device of claim 1 wherein the connection of the first set of hubs and the plate comprises movement guides, the position of this first set of hubs being adjustable relative to the plate.
 10. *Self-adjustable backrest device of claim 1 wherein the connection of the second set of hubs and the support comprises movement guides, the position of this second set of hubs being adjustable relative to the plate.
 11. Self-adjustable backrest device of claim 1 wherein it has more than one plate.
 12. Self-adjustable backrest device of claim 1 wherein the shaft is disposed at a distance from the seat surface (10) of between 18 and 27 cm. 